Many mixtures of caulking, grout, mortar or similar substances need to be mixed immediately prior to use. In some cases, the mixture hardens on exposure to air. In some cases, the mixture may lose its elasticity or its pseudo-plastic characteristics. In some cases, the material ‘flattens out’ or loses volume due to escape of gases generated by effervescence of the mixed material.
For example, if the end product is grout, a fresh mixture, immediately deposited, will resist shrinkage. The fresh mixture is slightly effervescent. If grout is mixed ahead of time, and then stored, the resulting mixture loses its effervescence over time, and then shrinks upon drying.
The need to mix materials immediately prior to use can result in inaccurate on-site measurement of constituent ingredients for the mixture, and hand-mixing of the ingredients in a bucket or the like can result in lumps of unmixed material clogging the nozzle of a caulking gun. Loading the mixture from a bucket into a bulk loading caulking gun can be a gritty, messy task, and the gun requires a thorough cleaning afterwards.
Similar reference numerals may have been used in different figures to denote similar components.